Method of treating vessels having refractory linings



Patented Jan.' 11, 1944 PATENT OFFICE METHOD F TREATIN G VESSELSREFRACTORY LININGS Frank Roberson, Gary, Ind. l Application June 27,1941, Serial No. 4400,140

2 Claims.

This invention relates to a method of treating vessels having refractorylinings, `such as blast furnaces, operi hearth furnaces, reheatingfurnaces, hot metal mixers, ladles, etc.

During the use of vessels having refractory linings, such as those ofthe type referred to immediately hereinbefore, the brickworkdisintegrates due to the infiltration of carbon monoxide (CO) gas.Within certain temperature limits, the carbon monoxide reacts upon theferric oxide tion referred to herein-before, followed by expan- (FezOs)of the refractory material, which is usualsion, with the result thatfrequently the'metallic ly present in the quantity of from 1.4 to 3 per.shell 6 is broken. It is commonly supposed that cent. This causes the'formation of carbon,'and the determining factor in the life of arefractory a consequent expansive effort which is sufficient brickworklining in a blast furnace is determined to cause destruction of. thebrickwork in particuby the wearing action of the coke on the bricklartemperature zones. It has been observed that work and the spalling andfusion 'of` the lbrick as the refractory lining warms up and thedifferdue to the high temperature of the furnace; but I ent verticalstrata pass through the range of from have reason to believe that thetrue determining approximately 400 to approximately 550 C., factor inthe life of such a refractory brickwork there results an extremelydeleterious effect upon lining is the disintegration of the brickworkby4 the brickwork which is .practically non-existent the factorsdiscussed hereinbefore. at temperatures below and above this range.According to the teachings of the present in- In the starting up of ablast furnace, there is a vention, I provide on the exterior of themetal- 4- or 5-hour period within which the different licshell B of theblast furnace anumber of ververtical strata pass through thistemperature tically-extending conduits having leadersconrange and thecarbon monoxide (CO) gas cracks necting with apertures I0 whichcommunicate and crumbles the brickworkas the successive laywith therefractory brickwork 5 of the furnace, ers pass through this zone. ,Inother words, if a Through these conduits 8 there is forced air at ablast furnace is taken out of service after a one`- pressure slightlyabove that inside the furnace.' week run and the lining removed, a veryhigh Thus at several different points on the periphery percentage of thebrickwork will show crumbling, of the refractory brickwork 5, air vispermitted spalling, and more serious disintegration along to filterthrough the bricks to prevent infiltration vertical seams where the-brickwork is constantly of carbon monoxide (CO) gas. It will be under'-held at a temperature of between approximately stood by those skilled inthe art that air is ef- 400 and 550 C. l l 35 fective for this pllrPOSe,and it may be convenient- It is among the objects of the presentinvention ly used because of its ease of supply at the correct to'prolongthe life of refractory linings of\ vestemperature and pressurefrom the cold -blast sels operating at high temperatures, such as main(not shown) of the furnace; but other mixthose specifically designatedhereinbefore'.' tures susceptible of neutralizing the effect of fur-Another object is to control the temperature 40 -nace gases may be used.gradient of refractories for lined vessels of the As a specific example,let it be supposed tha type described. j the pressure of the carbonmonoxide (C0) gas A further object is to prevent the infiltrationendeavoringto enter the refractory brickwork lininto refractorybrickwork of carbon monoxide ing 5 is 15 pounds per square inch and thepres- (CO) and other destructive gases, and thereby insure of theoutside air entering the lining in an crease the life ofl vessels withrefractory linings' opposite direction is 25 pounds per square inch.zones of which operate at temperatures of 400 C. There will result a10-pound differential which to 550 C. willbe suflicient to prevent theinfiltration of car- 'I'he foregoing and other objects will be apparbonmonoxide (CO) gas.' ent after referring to the drawing, in which theWhile the leaders 9 have been shown as so single gure is a sectionalview of a metallurgi-i cal blast furnace embodying apparatus which maybe used to practice the method of the present invention.`

Referring more particularly to thedrawing, the r Col. 26a-44),

numeral 2 designates the hearth or crucible of a metallurgical blastfurnace; the numeral 3 the bosh, and the Anumeral 4 the stack orlnwalls. All

of these portions of the blast furnace -are provided with a lining ofrefractory brickwork 5 which is covered by a metallicjacket 6; Due tothe infiltrationV of carbon monoxide (CO) and the reaction thereof onthe ferric oxide (EezOs) of the refractory, there results thedisintegraconnected as to provide air only to the stack or inwalls I, itwill be readily understood by those skilled in the art that similarconnections may be applied tothe boshA 3 which is disposed therebelow.

While Ivhave shown and .described a specific embodiment of the presentinvention, it will be seen that I do not wish to be limited exactlythereto. since various modifications may be made withoutdeparting` from.the scope of the invention 'as defined in the appended claims.

VI claim:

l. The method of treating blast furnaces lined with a refractorycontainingvferric oxide, said blast furnaces containing carbon monoxidein an amount sumcientto substantially attack the re-A fractory byreacting with the ferrie oxide whenV the refractory is at temperaturesof from between approximately 400C. to approximately B50"4 C.,which-includes forcing through the said l refractory portionsfrom `theexterior thereof a gaseous medium which is neutral to the refractory toprevent infiltration of carbon monoxide is neutral to the refractory toprevent inltration of carbon monoxide into the refractory portions whichare at the'said temperature range of approximately 400 C. toapproximately 550- C.

y@RANK ROBERSON.` l

